commit: c217649bf2d60ac119afd71d938278cffd55962b From: Mike Snitzer <[email protected]> Date: Thu, 13 Jan 2011 19:53:46 +0000 Subject: [PATCH] dm: dont take i_mutex to change device size
No longer needlessly hold md->bdev->bd_inode->i_mutex when changing the size of a DM device. This additional locking is unnecessary because i_size_write() is already protected by the existing critical section in dm_swap_table(). DM already has a reference on md->bdev so the associated bd_inode may be changed without lifetime concerns. A negative side-effect of having held md->bdev->bd_inode->i_mutex was that a concurrent DM device resize and flush (via fsync) would deadlock. Dropping md->bdev->bd_inode->i_mutex eliminates this potential for deadlock. The following reproducer no longer deadlocks: https://www.redhat.com/archives/dm-devel/2009-July/msg00284.html Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Mikulas Patocka <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]> Cc: [email protected] --- drivers/md/dm.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index f48a2f3..4ef066a 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1992,13 +1992,14 @@ static void event_callback(void *context) wake_up(&md->eventq); } +/* + * Protected by md->suspend_lock obtained by dm_swap_table(). + */ static void __set_size(struct mapped_device *md, sector_t size) { set_capacity(md->disk, size); - mutex_lock(&md->bdev->bd_inode->i_mutex); i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); - mutex_unlock(&md->bdev->bd_inode->i_mutex); } /* _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
